Ever since Ronald Reagan first said it, Republicans have been fond of insisting that "we don't have a revenue problem, we have a spending problem." But it turns out that isn't true. Let's take a look at the raw data.

Spending first. In 1981, when Reagan took office, the federal government spent 22.2 percent of GDP. That figure dropped steadily for the next two decades, and by the year 2000 spending was down to 18.2 percent of GDP. Expenditures went up after that, but the Office of Management and Budget estimates that by 2017, spending will once again be 22.2 percent of GDP, exactly the same as it was 30 years ago. In other words, spending hasn't gone up at all.

But even that overstates the problem. The chart below shows federal spending since the Reagan era. You'll notice a few things:

There are always small spikes during recessions. You see them in 1980, 1990, and 2000. This is perfectly natural: when the economy is bad, the federal government spends more on unemployment insurance, food stamps, Medicaid, and other forms of aid.

The first serious upward spike in spending came under George W. Bush and a Republican Congress. They were the ones who decided to fight two wars, enact a big Medicare expansion, and increase spending on other programs, both domestic and defense.

The other big upward spike came in 2008, and it was purely a temporary result of the Great Recession. This doesn't show that spending is out of control, just that the 2008 recession was bigger than any since the Great Depression.

But even with the 2008 recession, federal spending is still on track to be lower a decade from now than it was when Reagan took office. More details here. The plain fact is that spending simply hasn't been our big problem over the past three decades.

So how about tax revenue? The basic chart is below. It shows that tax revenue was 19.6 percent of GDP when Reagan took office, and it's projected to be 19.2 percent of GDP in 2017.

The facts are pretty clear. Spending isn't our big problem. The recession spike of 2008 aside, it's about the same as it was 30 years ago. But instead of paying for that spending, we've repeatedly cut taxes, which are now at their lowest level in half a century. Tax revenue will go up as the economy improves, but even five years from now it will still be lower than it was when Reagan took office.

So what's our real problem? That's simple: America is getting older and healthcare costs are rising. That means we'll need to spend more money in the future on Social Security and Medicare. There's simply no way around that unless we're willing to immiserate our elderly, and that's not going to happen. Not only is it politically inconceivable, but the truth is that even Republicans don't want to do it, no matter how tough a game they talk. Like it or not, this means that over the next 20 or 30 years, spending on the elderly is going to go up by three or four percent of GDP.

This is where we stand. Spending in general has been well controlled for the past 30 years, averaging about 21 percent of GDP. With good management, that might go down a point or two, but certainly no more. Probably the lowest we can realistically hope for is about 19-20 percent of GDP. Add in the increased spending on the elderly, and federal outlays are going to be in the neighborhood of 23-24 percent of GDP by around 2030.

Those are simply the facts. Even under a scenario where we control spending pretty tightly, spending is going to go up to about 24 percent of GDP. There's really no politically feasible way of keeping it any lower. Anyone who cares about the deficit, then, needs to understand that in the long run, taxes need to go up to about 24 percent of GDP too.

We don't have a spending problem. We have an aging problem and a taxing problem.

A good interview gives us access to people and ideas that often stay behind the curtain. But it can do more than that: As British journalist Lynn Barber has said, that the best interviews "sing the strangeness and variety of the human race." We certainly covered both this year, chatting up everyone from children's author Phillip Pullman to adventurer Felicity Aston to rising star of comedy W. Kamau Bell. Here are 12 of our favorites from 2012, one for each month, with even more below. We hope you have as much fun exploring them as we had talking to these fascinating and talented people.

For some reason, the possibility of evading the debt ceiling by minting a $1 trillion platinum coin is getting some blogospheric love again. This is based on a 2000 revision to the U.S. statute on money and finance that reads:

The Secretary may mint and issue bullion and proof platinum coins in accordance with such specifications, designs, varieties, quantities, denominations, and inscriptions as the Secretary, in the Secretary’s discretion, may prescribe from time to time.

Read literally, this places no limitations on the Treasury Secretary's authority to mint platinum coins. If Tim Geithner wants to mint a $1 trillion coin and deposit it at the Fed, he can do it.

I would just like to point out, once again, that this is ridiculous. During the very short floor debate on this amendment it was repeatedly referred to as a "technical correction," and that's obviously what was intended. Oklahoma Rep. Frank Lucas described it this way:

Also contained in the bill is a clarifying section inserting the word ‘‘platinum’’ inadvertently dropped when Congress authorized production of platinum and platinum bullion coins a few years ago....This is a small bill, but important to the mint and important to coin collectors. It has no cost implications whatsoever.

No particular restrictions were placed on the design or issuance of platinum coins, but this paragraph was plainly intended to apply to bullion and commemorative issues for coin collectors. That's all.

There is, apparently, a widespread belief that courts will uphold a literal, hypertechnical reading of legislative language regardless of its obvious intent, but I'm quite certain this isn't true. Courts are expected to rule based on the most sensible interpretation of a law, not its most tortured possible construction. I don't think there's even a remote chance that any court in the country would uphold a Treasury reading of this law that used it as a pretense for minting a $1 trillion coin.

I am, obviously, not a lawyer. So if someone with actual legal training in the appropriate area of the law says I'm wrong, then I guess I'm wrong. But I'm not much afraid of that happening. This whole notion is the kind of thing that Herman Cain would come up with. It's time to stop treating it seriously.

A couple of months ago I linked to a bit of research showing the effect of gerrymandering on House races. Long story short, Eric McGhee concluded that gerrymandering produced about 7 extra Republican seats this year while Sam Wang figured it at about 6.3 seats. A few days ago, Sam took a deeper dive into the data (read his full post if you want to understand his simulation methodology) and came up with a bit more detail about how that breaks down. His bottom line number is now slightly higher than it was before, showing a Republican advantage of about 7.1 seats, but the reason this number is so low is a little surprising. I've modified his main results table a bit for the nine states that show a substantial discrepancy between vote share and seat share. Here it is:

D %vote

D sim

R sim

D seats

R seats

Discrepancy

Pennsylvania

50.7%

8.4

9.6

5

13

R+3.4

Texas

39.9%

9.4

26.6

12

24

D+2.6

Ohio

47.9%

6.5

9.5

4

12

R+2.5

North Carolina

50.9%

6.2

6.8

4

9

R+2.2

Michigan

52.7%

7.2

6.8

5

9

R+2.2

Arizona

45.6%

3.2

5.8

5

4

D+1.8

Virginia

49.0%

3.7

5.3

2

7

R+1.7

Illinois

55.4%

10.3

7.7

12

6

D+1.7

Indiana

45.8%

3.2

5.8

2

7

R+1.2

Nonpartisan

D+4.4

D-controlled

D+1.7

R-controlled

R+13.2

Net, all 9 states

48.5%

58.1

83.9

51

91

R+7.1

There was serious gerrymandering in only one Democratic state: Illinois, for a total advantage of 1.7 seats. But there was serious gerrymandering in six Republican states, for a total advantage of 13.2 seats. Republicans tried hard to gerrymander themselves into a majority, but it turned out that two nonpartisan states (a commission in Arizona and a court in Texas) ended up producing 4.4 extra Democratic seats.

Bottom line: The net result is still fairly modest, thanks to the vagaries of nonpartisan redistricting. At the same time, the effect of partisan gerrymandering is larger than we thought. The sum of Democratic and Republican gerrymandering is a net Republican advantage of 11.5 seats. That's still not enough to say that the Republican House majority is solely due to gerrymandering, but it's close.

Mother Jones' Washington, DC bureau chief David Corn joined Bloomberg View columnist Jonathan Alter on MSNBC's Martin Bashir Thursday to discuss whether the newly sworn-in 113th Congress will actually be able to get stuff done (such as Part 2 of a fiscal deal), or whether this session will be more of the same. Corn is not too optimistic. "The leadership of the new Congress is same as it was," he said. "If anything it's more fractious." In the House especially, "Boehner can't negotiate because he can't control his own caucus. The fiscal deal just cut to chagrin of tea party will only embolden [the tea party] further when it comes to the debt ceiling, making them more unmanageable in next few weeks." Watch here:

Keith Humphreys has a nomination for the most underreported public policy story of the past year: The continuing decline in the number of Americans who are behind bars or on probation/parole. Alex Tabarrok illustrates the trend with the chart on the right.

What's going on? At the risk of sounding like a broken record today, part of the answer is probably lead. Lead emissions rose throughout the 50s and 60s, leading to a rise in crime through the 70s and 80s. Incarceration rates went up dramatically during the high-crime years, and many of the people put behind bars served long sentences. So even though crime rates started to fall in the early 90s, incarceration rates kept going up for a while as new criminals were added to a system that already had a lot of long-term residents.

Eventually that turned around, and the incarceration rate turned around too. But it turns out there's actually something even more interesting going on if you dig into the data. Rick Nevin, one of the lead researchers who played a key role in figuring out the lead-crime connection, has a short paper about incarceration rates at his website, and his key point is this: over the past decade, incarceration rates for young offenders have gone down, while incarceration rates for older offenders have remained high. (In fact, they're actually up a bit, probably the result of recidivism.) The chart below shows the raw data:

Note how this fits the lead hypothesis. Young people, who were raised in the post-lead era, have sharply lower arrest rates than in the past and sharply lower prison rates. At the same time, older people, who were raised during the era when lead emissions were high, still have high arrest rates and therefore high incarceration rates. However, as the oldsters serve out their sentences and finally get too old for criminal activity, the lower arrest rates of young people are finally lowering overall incarceration rates. Nevin explains more in his paper, and also added a comment to my article with some additional details about black-white incarceration trends between 2001-11:

Over the same 10 years , the incarceration rate for black men ages 18 and 19 fell by 46%, and fell 40% for black men ages 20-24, and 31% for black ages 25-29. Over that same 10 years, the incarceration rate for black men ages 35-39 fell 12% and the rate for black men age 40-44 increased 11%.

....The incarceration rate is now declining for black males ages 35-39, but rising for white males in that age bracket, because that age group today reflects years when slum demolition in black neighborhoods reduced severe lead paint hazards over the 1960s, as urban sprawl caused more gasoline lead fallout in predominantly white suburbs.

You will often hear inaccurate and misleading statistics about the lifetime risk of incarceration for black males. That data reflects what the risk of incarceration was for black males born across years of pandemic lead poisoning, in urban slums with severe lead paint hazards and additive exposure to urban gasoline lead fallout. That "lifetime risk" does not apply to young black males today.

I'm going to caution everyone again that no one is suggesting that lead is solely responsible for the rise and fall of either crime rates or incarceration rates. There are plenty of other factors. But the evidence is very strong that lead plays a key role. And the good news is that since the drop in lead emissions is permanent, crime rates are likely to stay fairly low and incarceration rates are likely to continue to fall. Someday, instead of hearing about overcrowded prisons, we'll be tearing down old prisons because there aren't enough inmates left to keep them in business.

Congress may have averted the fiscal cliff, but when it comes to ugly fiscal battles, America hasn't seen anything yet, according to Mother Jones Washington Bureau Chief David Corn. "The Republicans now are going to be out for blood" Corn says. "Having lost this round as they are see it, they are going to want to have a big fight over the debt ceiling and to demand it's not raised."

“I will look much more carefully at the Illinois Medicaid program to see how my fellow citizens are being cared for who have no income and if they suffer from a stroke,” Kirk said.

He said in general a person on Medicaid would be allowed 11 rehab visits in Illinois. “Had I been limited to that I would have had no chance to recover like I did. So unlike before suffering the stroke, I’m much more focused on Medicaid and what my fellow citizens face.” [italics added.]

Harold says that this comment "commands respect," and in one way, of course it does. But in another way, it's one of my big bugbears. Politicians all seem to have their own pet causes, and all too often they're related to something personal. A congressman's wife had breast cancer, so he supports funding for breast cancer research. A senator's kid has multiple sclerosis, so she supports MS research. A governor's state gets hit with a hurricane, so he supports a huge federal aid bill for hurricane damage. This goes on and on and on.

But too many politicians, and this especially includes self-described fiscal conservatives, simply can't draw the obvious conclusion from all this: namely that you shouldn't support help for the poor and the sick and elderly only if you personally happen to know someone who's poor or sick or elderly. All of these people exist whether or not they happen to be family members.

So I'd suggest to Kirk that he broaden his horizons. Making sure that Medicaid helps stroke victims is a great idea. But an even better idea is making sure that Medicaid also helps victims of diseases that Mark Kirk hasn't personally confronted. Medicaid should help everyone. It's not just a plaything for a small subset of pet causes.

And while I'm on the subject, there are a couple of quick items I'd like to mention that may or may not have been clear from my article:

Am I saying that gasoline lead is fully responsible for the nationwide drop in violent crime over the past two decades? No. Absolutely not. There are plenty of other factors, including the end of the crack epidemic, changes in policing tactics, higher incarceration rates, and more. The precise effect of all these things is a matter of controversy, but they almost certainly all played a role. However, I am saying that they probably played a smaller role than we think.

Is the lead-crime connection 100% proven? No. However, the evidence, which started out fairly thin ten years ago, is now quite extensive. In fact, one of my motivations for writing this piece was the fact that the criminology community has paid very little attention to the lead hypothesis, and I think it's time they did. If it's wrong, they should do the research to show that it's wrong. But if it's right, that should change the way we look at other crime-fighting tactics. Change #1, in my opinion, would be our current policy of mass incarceration, which quite likely had done as much good as it would ever do by the mid-80s. Given the decline in violence over the past two decades, and the possibility that it's probably due to a permanent decrease in lead emissions, it's quite likely that we could safely cut back on incarceration rates at this point.